1. Field of the Invention
This invention relates generally to reproducing musical performance on keyboard operated musical instruments, and more specifically to measuring the velocity and timing of movement of the keys.
2. Description of the Background Art
In order to reproduce musical performances with more accuracy and realism of expression on a keyboard operated musical instrument, it is essential to have accurate key movement velocity information. Expression, which is a function of the velocity of movement of the key, comprises dynamic changes in volume and playing force, which affects overall volume and tonal quality. For example, in a piano, expression is determined by the velocity of the hammer striking the strings. Therefore, not only must the musical notes and their timing be determined, but the expression contained in the original work must be measured in order to re-recreate a more realistic performance.
Examples of methods and apparatus for recording expression effects can be seen in Campbell et al. U.S. Pat. No. 4,172,403 issued on Oct. 30, 1979, which discloses a method and apparatus for encoding expression data while recording from the keyboard of an electronic player piano wherein the intensity of the music being recorded is reflected in variations in the power of the acoustic waveform produced. Campbell et al. U.S. Pat. No. 4,176,578 issued on Dec. 4, 1979, discloses a system for encoding of bass and treble expression effects in a digital data stream while recording from the keyboard of an electronic player piano. Campbell U.S. Pat. No. 4,174,652 issued on Nov. 20, 1979, discloses a method and apparatus for recording digital signals for later actuating solenoids for re-creation of musical expression. Ohe U.S Pat. No. 4,419,920 issued on Dec. 13, 1983, discloses an apparatus for recording and reproducing musical performances in which the recording comprises the image, the sound, and musical instrument performance data of a particular performance, the watcher-listener being able to see and hear the performance via a video playback and the automatic playing of an actual musical instrument. Starnes et al. U.S. Pat. No. 4,351,221 issued on Sep. 28, 1982, discloses a player piano recording system which has photosensor flags secured to the underside of the piano keys, vertical movement of which is detected by horizontally adjustable photosensors to produce "key played" and key velocity signals which are supplied to a microprocessor for deriving expression signals for recording on magnetic tape.
A limitation of the foregoing methods and devices, however, is that the sensors used can only detect a change in position of the key and, in order to determine the velocity of key movement, it is necessary to calculate velocity based on the timing of the different key positions. This leads to inaccuracies in velocity calculations due to differences in the amount of key stroke as well as difficulty in reproducing notes which were played with a partial key press.
Therefore, there exists a need for a device and technique for recording key velocity without regard to length of stroke or position of the key. The present invention overcomes the deficiencies in the devices and techniques heretofore developed, and provides for accurate recorded of the velocity of key motion in a keyboard operated musical instrument.
The foregoing patents reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully stipulated, however, that none of these patents teach or render obvious, singly or when considered in combination, applicant's claimed invention.